Combine dressing: zest, lemon juice, oil, honey, mustard, salt, and pepper in a cup, stir well, remove about 1/4 cup of dressing mixture and put into medium size bowl for salad for step 2. RESERVE rest of dressing for topping tomato/avocado mixture later for Step 4.
Into medium sized bowl ( that you have the 1/4 cup of dressing), add the additional 3 tablespoons of lemon juice, corn, basil, bell pepper, onion, and crab; toss gently.
Arrange 2 tomato slices and 1/4 avocado onto each of 4 plates.
Drizzle about 1 teaspoon of reserved dressing in cup over each tomato/avocado mixture.